Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
Meio University, 1220-1 Bimata, Nago, Okinawa 905-8585, Japan.
Sci Total Environ. 2020 Oct 15;739:140049. doi: 10.1016/j.scitotenv.2020.140049. Epub 2020 Jun 6.
The present study determined contamination levels of POPs, such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs), in oysters (Saccostrea mordax) collected throughout the seacoast of Okinawa, Japan and their geographic distribution. PCBs, DDTs, CHLs, PBDEs and HBCDs were detected in almost all the oyster samples analyzed and higher concentrations of PCBs, DDTs and CHLs were found in oysters from southwestern populated areas. On the other hand, HBCDs in oysters showed similar levels throughout Okinawa and the highest concentration in a northern rural site with less human and industrial activities, although oyster concentrations of PBDEs were relatively lower. When POPs in expanded polystyrene (EPS) buoys and polystyrene foam debris floated and drifted on coastal seawater were analyzed, extremely high concentrations of HBCDs were detected in some of these EPS buoys and polystyrene foam debris but other POPs were below the limit of detection in all the samples. To evaluate the specific exposure route of HBCDs for oysters, we further analyzed HBCD diastereomers, and PCB congeners by way of comparison, in seawater and sediment samples collected at an urban site and a rural site and estimated their biota (oyster)-sediment accumulation factors (BSAF) and bioaccumulation factors (BAF). Interestingly, the highest log BAF values were found for α-HBCD despite its lower log Kow than those of γ-HBCD and PCB congeners, although log BSAF values for HBCDs were lower than those for PCBs. Considering that α-HBCD was detected in a few polystyrene foam samples as the predominant diastereomer, oysters inhabiting the coastal region of Okinawa might be frequently exposed to micronized polystyrene foam particles containing HBCDs.
本研究测定了日本冲绳沿海牡蛎（Saccostrea mordax）中持久性有机污染物（POPs）如多氯联苯（PCBs）、滴滴涕及其代谢物（DDTs）、氯丹化合物（CHLs）、多溴联苯醚（PBDEs）和六溴环十二烷（HBCDs）的污染水平及其地理分布。在分析的几乎所有牡蛎样本中都检测到了 PCBs、DDTs、CHLs、PBDEs 和 HBCDs，而在西南部人口稠密地区的牡蛎中发现了更高浓度的 PCBs、DDTs 和 CHLs。另一方面，HBCDs 在整个冲绳的牡蛎中水平相似，在人类和工业活动较少的北部农村地区含量最高，尽管牡蛎中 PBDEs 的浓度相对较低。当分析漂浮和漂流在沿海水域的膨胀聚苯乙烯（EPS）浮标和聚苯乙烯泡沫碎片中的 POPs 时，在一些 EPS 浮标和聚苯乙烯泡沫碎片中检测到了极高浓度的 HBCDs，但在所有样本中其他 POPs 的浓度都低于检测限。为了评估 HBCDs 对牡蛎的特定暴露途径，我们进一步分析了在城市和农村地点采集的海水和沉积物样本中的 HBCD 对映异构体和 PCB 同系物，并通过比较估算了它们的生物群（牡蛎）-沉积物积累因子（BSAF）和生物积累因子（BAF）。有趣的是，尽管 α-HBCD 的 log Kow 值低于 γ-HBCD 和 PCB 同系物，但它的 log BAF 值最高，尽管 HBCDs 的 log BSAF 值低于 PCB 同系物。考虑到 α-HBCD 是少数聚苯乙烯泡沫样本中的主要对映异构体，生活在冲绳沿海地区的牡蛎可能经常暴露于含有 HBCDs 的微粒化聚苯乙烯泡沫颗粒中。
